[Patent document 1] JP-2003-312553 A
For example, Patent document 1 describes a vehicular data record apparatus which records vehicle information before and after an emergency such as an action sudden change. This vehicular data record apparatus contains a vehicle data storage area having several rewritable archive blocks where vehicle data are rewritable, and an action sudden change occurrence detection device which detects an occurrence of a vehicular action sudden change such as an anomalous start-up and a sudden deceleration movement, which do not result in an accident.
The apparatus selects a archive block in the vehicle data storage area, and records vehicle data one by one in the selected archive block. When it is detected that a check-needed state such as an action sudden change occurs in the vehicle, another archive block is newly selected and the recording of vehicle data is then started. In such a case, the recording to the archive block that has been used before the check-needed state is detected is stopped after a predetermined time period elapses since the check-needed state is detected. Thus, even when the check-needed states occur successively, the vehicle data can be stored appropriately.
In the above vehicular data record apparatus, only on the condition that an action sudden change arises, the vehicle data at the time of the action sudden change is recorded in a single archive block, and the archive destination of the vehicle data is changed into another archive block. Such changes of the archive blocks may result in a state where the vehicle data are recorded in all the archive blocks. In this case, when another new vehicle data needs to be further recorded, the vehicle data is written over the archive block which records the oldest vehicle data.
An example is considered that a sudden acceleration occurs in a vehicle because a driver mistakenly steps on an accelerator pedal instead of a brake pedal. In such a case, a driver becomes in a panic state since the vehicle accelerates suddenly although the driver believes to have stepped on the brake pedal. The driver may further repeat mistakes such as stepping on the accelerator pedal farther or repeating of stepping on the accelerator pedal. In the case of stepping on the accelerator farther, the vehicle further accelerates; in the case of repeating of stepping on the accelerator pedal, the vehicle decelerates suddenly when departing from the pedal and accelerates suddenly when repeating of stepping on the pedal.
In order to correctly execute an after-the-fact analysis of the cause of such a state, it is desirable to obtain a series of or a group of vehicle data chronologically from when the first sudden acceleration occurs to when the anomalous action of the vehicle arises thereafter.
However, the vehicular data record apparatus in Patent document 1 changes the archive destination into a different archive block only on the condition that an action sudden change arises, as mentioned above. Thus, a series of vehicle data and an independent vehicle data irrelevant to the series of vehicle data may be recorded in a mutually mixed state. In other words, both the series of vehicle data and the different independent vehicle data are recorded at the same time in the vehicle data storage area; thus, it becomes difficult to investigate a true cause of the vehicle action sudden change.